Steel bridge on roadway bridge(at sole plate) のバックアップ(No.2)

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Steel bridge on roadway bridge(at sole plate) へ行く。
- 1 (2014-04-23 (水) 13:32:26)
- 2 (2014-04-23 (水) 14:43:28)
- 3 (2014-04-23 (水) 17:24:03)
- 4 (2014-04-24 (木) 12:55:37)

Steel bridge on roadway bridge(at sole plate) †

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1.Field of application †

Steel bridge on the roadway bridge,Japan.

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2.Circumstances of Repair †

Fatigue cracks were found in the sole plate welds at the girder support locations in 1990 after 22 years of service.

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3.Types of structure †

The outline of the bridge structure is as follows.

Bridge length : 114.864m

Span length : 35.0m+44.0m+35.0m

Structure : Three spans continuous girder bridge.

Structural steel : SM490A,SM490B,SS400

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4.Details of loading †

Fluctuating loads due to vehicles live load.

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5.Description of damage †

The location where the fatigue cracks were found were as follows.

The fillet welding joint at the front side of the sole plate(Type-1).

The fillet welding joint between the lower flange and the web(Type-2).

Type-1 crack penetrated the lower flange.

Most of the cracks initiated from the weld in front of the sole plate. Only a few cracks which initiated from the girder web-flange weld are observed. After penetrating through the girder bottom flange, the cracks which initiated from the welds in front of the sole plate had propagated at an angle in the girder web(Fig.2). At the time of discovery, Both the movable supports and the fixed bearings lost the function as supports and the subsidence of the shoe base was also observed.

Cause of fatigue cracks was as follows:

Stress concentration due to the subsidence and lost of the support function.

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Fig.2 Crack propagating in the girder web from the sole plate weld.

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6.Repair method applied †

As an emergency repair, temporary support bent was constructed for the cracks which propagated to the girder web.

As a permanent repair, strengthening was as follow (Fig.3,4).

Removing the pin support and replacing with new BP (Bearing plate) supports.

Replacing with the large sole plates and bolt-connecting to the girder bottom flange.

Bolt-splicing after being refilled by welding.

File not found: "Shinde5.jpg" at page "Steel bridge on roadway bridge(at sole plate)"[ź��]

Fig.3 Permanent repair.

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Fig.4 Repair view.